Last week, a story in the NY Times alluded to the fact that Opera mini had bee rejected by Apple because it "competes with Safari". Mac insider John Gruber of Daring Fireball did some digging and according to his sources, Opera Software has not submitted Opera Mini to Apple. Gruber goes on to say that if Opera Mini were submitted, it could very well be declined for violating guideline 3.3.2  of the iPhone SDK Agreement.

3.3.2 — An Application may not itself install or launch other executable code by any means, including without limitation through the use of a plug-in architecture, calling other frameworks, other APIs or otherwise. No interpreted code may be downloaded and used in an Application except for code that is interpreted and run by Apple’s Published APIs and built-in interpreter(s).

The Opera Mini browser relies on running Java and the iPhone does not support Java in any form. For Android, Opera Software has developed their own bridge to run Java ME. For the app to be considered for the iPhone, it would have to be ported to C and Objective-C API's.

via Daring Fireball